This application is filed under the provisions of 35 U.S.C. xc2xa7371 and claims the priority of International Patent Application No. PCT/DE00/00880 filed Mar. 17, 2000, which in turn claims priority of German Paten Application No. 299 06 012.8 filed Apr. 1, 1999.
The invention pertains to a protecting cap for the head of a screw that is screwed into a constructional part.
Numerous designs of protecting caps for screw heads are known. These protecting caps are usually realized in the form of injection molded plastic parts that can be placed onto the screw head due to their ductility and protect the screw head from soiling, corrosion and mechanical damages. One disadvantage of known protecting caps can be seen in the fact that they do not remain firmly seated over time. Aging of the cap material can cause the protecting cap to become loose, in particular, under the influence of vibrations or other mechanical effects.
U.S. Pat. No. 5,707,113 pertains to protecting and mounting caps for hubcaps. The protecting caps are placed onto the protruding threaded bolts of the wheels that are mounted with screws. In one preferred embodiment, the protecting cap of plastic contains an inner metal clip that is engaged with the thread after the protecting cap is attached.
FR-A-2 086 693 pertains to a cover plate for a screw. In this case, a lower part is fixed on the substrate by means of the screw to be covered. Subsequently, a cap is attached and held by the lower part. The lower part is not arranged between the lateral surfaces of the screw head and the inner side of the surface area of the protecting cap, but rather held on the substrate due to the clamping effect of the screw.
DE 1 137 098 pertains to facing elements for covering electrical devices. This document discloses a holding device that comprises encompassing springable parts that are held on the substrate by mounting screws and into which pins that are tapered within the central section can be inserted. The encompassing springable parts are not arranged between the lateral surface of the screw head and the inner side of the surface area of the protecting cap.
U.S. Pat. No. 4,784,555 pertains to a cover plate for screws and bolts. In this case, a O-ring is arranged on the inner side of the cap. The inside diameter of the O-ring is smaller than the outside diameter of the bolt. In order to achieve a non-positive connection between the cap and the O-ring, the inner side of the cap contains a groove, into which the O-ring engages.
The present invention is based on the objective of developing a protecting cap for the head of a screw which is held on the screw head by means of a firm press fit. The invention also aims to provide a protecting cap that remains securely seated even at elevated temperatures. Additional advantages of the protecting cap according to the invention are disclosed in the following description.
According to the invention, this objective is attained with a protecting cap of the initially described type due to the fact that a body is arranged between the protecting cap and the screw head which produces a positive or non-positive fit between the protecting cap and the screw head. In order to fulfill its function, the body has a sufficient elasticity for holding the cap on the screw head. The shape of the screw head and the protecting cap may differ, i.e., the body used for producing the connection needs to be correspondingly adapted. The screw head may, in particular, have a cylindrical or hexagonal-prismatic shape. The connection is, in principle, designed such that the protecting cap can be manually attached and detached, but unable to detach on its own under the respective operating conditions.
In one preferred embodiment of the protecting cap according to the invention, the body is realized in the form of a ring or cap of an elastic material and arranged between the lateral surface of the screw head and the inner side of the surface area of the protecting cap. The ring or cap may consist of rubber or an elastomer plasticmaterial. This body can be permanently fixed in the protecting cap during its manufacture such that it does not have to be attached onto the screw head separately of the protecting cap. The elastic ring is subjected to a clamping effect when the protecting cap is attached and thusly produces a secure connection between the cap and the screw head. If the body can be subjected to a thermal load, e.g., up to 220xc2x0 C., the protecting cap is also securely held on the screw head at elevated permanent temperatures.
In one special embodiment of the protecting cap for a screw head situated in a flat sink, the protecting cap has such dimensions that the sink is sealed in a flush and essentially gap-free fashion. In this case, the outside diameter of the protecting cap corresponds to the inside diameter of the sink, and the height of the protecting cap corresponds to the depth of the sink. The protecting cap not only protects the screw head, but also completely fills out the sink such that an appealing and barely visible appearance of the screw connection is achieved.